Development of tunable hybrid magnet for biasing of 505.8 MHZ ferrite circulator

The tunable hybrid magnet has been developed for the biasing of ferrite circulator. The required tunable magnetic field is generated in pole aperture using the combination of strontium ferrite permanent magnet disks and pole coils. The magnet design parameters were optimized using Opera 3D Tosca solver to generate 1000 Gauss to 1500 Gauss field in the pole gap of 85 mm. The magnet has been used in the biasing of 505.8 MHz ferrite circulator for high power operation up to 26 kW. This paper presents the details of tunable hybrid magnet design, its development, magnetic field measurement results and its operation in circulator testing. (author)